Mexican officials apparently are floating the possibility that jailed Marine Andrew Tahmooressi could avoid a lengthy prison term, if -- and only if -- he blames the entire episode on post-traumatic stress disorder.

Rep. Duncan Hunter, R-Calif., revealed the development in a letter sent Monday to Marine Corps Commandant Gen. James Amos.

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Relaying the details of discussions he's had with Mexican officials on the case, Hunter wrote: "It was conveyed to me that the only way Andrew can avoid an extended prison sentence is by stating that PTSD was the reason for his mistake."

Tahmooressi has been detained in Mexico for more than two months now, after taking a wrong turn and ending up on the southern side of the border -- he was carrying legally purchased guns, but was charged for weapons trafficking.

The U.S. Marine and combat veteran says he entered Mexico by accident, but the pleas -- and involvement by U.S. State Department officials and lawmakers -- so far have not convinced the Mexican government.

His mother Jill Tahmooressi says Andrew does have PTSD; he had been in San Diego to receive treatment for it.

But it's unclear whether his legal team -- which recently changed after the jailed Marine fired his old lawyer -- would use that as a possible defense.

As FoxNews.com previously reported, the new attorney Lamberto Jesus Esquer Dabdoub is planning to look at the prolonged amount of time Tahmooressi was held at the border in the custody of the Mexican military on March 31, in what Tahmooressi felt was a failed shakedown.

Without speculating on whether the legal team should use PTSD as a defense, Hunter urged Amos to "match words with action," given the public attention on PTSD in general.

"Andrew's case represents a call to action and we, including the Marine Corps as an institution, have an obligation to ensure he receives our full support," he wrote.

Specifically, he urged Amos to "communicate" his support for Tahmooressi to the State Department, President Obama and Mexican military officials.

Hunter also stressed that the treatment Tahmooressi was receiving was "no different" than that sought by "many other Marines who have received the same diagnosis over the course of more than a decade of combat."

Jill Tahmooressi told FoxNews.com last month that the wrong turn her son took could have been caused by a side effect of severe concussions he sustained while in combat in Afghanistan.